Dc to Dc - Double Check Me Please

[Swamplizard]

Good morning All!

Picked up a Orion 12/24 10Amp DC to DC Isolated charger. Read the manual twice and want to make certain I have this right before I install.

Conversion Van is a diesel with traditional 12V systems. Alternator is a "dumb" 190Amp unit at 12V. Starter battery is a very large sealed AGM at 12V under the floor of driver in a ventilated space. Manual recommends putting it as close to starter battery as possible.

House power is 24V LIFEPO4 which is 16 feet away in the rear of the Van.

PLAN: Install the DC to DC unit next to battery (yes it is vented space) and run 12-volt 8AWG to battery bus with a 20Amp fuse. 8AWG to vehicle ground bus as well. Then run 6AWG positive and negative to 24-volt battery bus and 24-volt BMS. Will also run a 12-volt 14AWG positive wire to cigarette lighter circuit which is only hot when key is on.

Any issues with this install plan?

As always - MANY thanks!

Swampy

 

[John Frum]

Good morning All!

Picked up a Orion 12/24 10Amp DC to DC Isolated charger. Read the manual twice and want to make certain I have this right before I install.

Conversion Van is a diesel with traditional 12V systems. Alternator is a "dumb" 190Amp unit at 12V. Starter battery is a very large sealed AGM at 12V under the floor of driver in a ventilated space. Manual recommends putting it as close to starter battery as possible.

That is very unusual.
Please link to the manual.

Even though the voltage drop will be higher on the 12 volt(input) side, usually a dc2dc charger is located as close as possible to the battery being charged(house battery) not the starter battery/alternator.
The charger can compensate(within reason) for the voltage drop on the input side.
Unless it has sense leads it can't compensate for voltage drop on the output side.
Hope that is clear.

 

[John Frum]

For that length you should bump the wires up to 6 awg to get < 3% voltage drop.

 

[Swamplizard]

Thanks SmoothJoey. Looks like I need to re-read it or contact victron. I assumed as long as fuses and wire gauge were correct it didnt matter where it was and front seemed easier. Thanks for the double check!

 

[RCinFLA]

The charger needs to accurately apply absorb and float voltage to battery. If there is some voltage drop due to charging current to battery those voltages will be less at battery.

You will have a little less than half the 12v input current on the 24v output side of charger. For 240 watt charger that is a bit less than 10 amps.

If the voltage drop from charger to 24v battery is small (<0.1v) you can do what you outlined.,

16 feet of #6 (x2 for + & - cables) at 10 amps is 0.13 v drop. Doubling up on at least one of the two wires would keep within 0.1v drop.

I would be also careful of getting road slop on the charger. Salted slush would not be good.